Glad to help and thank you for the quick response, @ERACSGracie!

Let me help you be able to convert your invoice template successfully. 

First off, you're right about QuickBooks Online not importing your invoice template after copying it to MS Word. Because they have different platforms and templates doesn't have the same formats.

With this, you'll need to search for a converter application or software. And then, install it on your Desktop computer.

From there, you can convert QuickBooks Desktop invoice template and then import it to your QuickBooks Online.

Let me know if you have any other questions about your invoice template. I'll be always happy to help you out.